In recent radio communication schemes such as HSDPA (High-Speed Downlink Packet Access), some measurements for conditions in downlink radio channels (referred to as CQIs (Channel Quality Indicators) hereinafter), are reported from mobile stations to base stations. For example, see a publication written in Japanese “W-CDMA mobile communication schemes” edited by Keiji Tachikawa, published by Maruzen, pp. 403-404, June 2001.